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NITED STATES PATENT rricni CARL LOWIG, OF BRESLAU, PBUSSIA, GERIVIANY.

SPECIFICATION forming part of Letters Application filed October 20, 1882.

To all whom it may concern Be it known that I, CARL LiiWIG, of Eros-- lau, Kingdom of Prussia, German Empire, have invented an Improvement in the Process of Manufacturing Caustic Alkalies, of which the following'is a specification.

If a mixture of carbonate of soda or carbonate of potash with oxide of iron is exposed to every high heat, a chemical compound or combination is obtained,while carbonic acid is developed of oxide of iron with soda or potash, which compound or combination, if treated with water, is decomposed into caustic soda or caustic potash (which are dissolved in the water) and into oxide of iron. On these facts my improved process is based for manufacturing on a large scale and for industrial purposes caustic alkalies.

My process is noted for the simplicity and facility of its working, inasmuch as the canstics or lyes gained by it are readyfor immediate evaporation without any intermediate operation, and the oxide of iron regained maybe reused for the next process.

The first condition for working according to my process is to have pure or nearly pure oxide of iron, whether artificial or natural.

- The same should not contain either alumina or silica. A small percentage of chalk or magnesia is without any injurious influence.

I have ascertainedbynumerous experiments that for the manufacturing of caustic alkalies a mixture of one molecule of carbonate of potare used in gas-works, and the heating of the same is done in the similar manner. The heat mustbe raised up to bright cherry heat.

In manufacturing pure caustic alkalies it is advisable to heat twice and to regrind and sift the mixture again after the first heating. The active heating must be continued for about one hour, or for such a period that a trial with diluted acid will produce no eft'ervescence.

Patent No. 274,619, dated March 2'7, 1883.

(No specimens.) Patented in France September 14, 1882, No. 151,086, vand in Belgium September 14,

Heating in cylinders, at all events, is to be preferred to heating in an open oven or in a bauxite oven; but care must be taken that the cylinder is perfectly filled with the mixture and is broughtnniforrnly in its entire length up to bright cherry heat. If the oxide of iron is pure, the mixture will stand a very high temperature without becoming soft or scorificating. This will not be the oase'if the oxide of iron contains ten to twelve per cent. of silica. The lixiviation of the heated mass is preferably offected in a vessel provided with a stirring or agitating apparatus with iron blades and having pipes for the admission of steam. In manufacturing on an enlarged scale it is preferable to employ two such vessels for alternate use. The vessel is first filled with hot water or with diluted lye up to two-thirds or three-quarters of its bulk, and hereinto the mass, after the same has undergone the heating process, is introduced. During this adding of the mass into paratus must be continuously and rapidly worked, and steam must be admitted. The addition of the material is stopped if the lye has arrived at the desired degrees shown by the areometer. Stirring must be continued for, say, half an an hour or-three-quarters of an hour, and the temperature must be kept up'to 90 Celsius, (194i Fahrenheit.) The agitator is now stopped, and after about one quarter or half an hour the clear lye is drawn oft into an iron vessel for settling until the lye has arrived at perfect clearness. l t is advisable to ascertain before evaporation of the lye whether any iron is contained in it, which is done by adding to a small quantity of it a few drops of a solution of hydrosulphuret of ammonia. The presence of iron will by this addition be demonstrated by a dark color, and in this case the lye has to remain still for some time in a warm state. If the solutions of caustic alkaacid, the lattermay be removed by carefully adding caustic baryte. The oxide of iron remaiuing and regained after the lixiviation is more or less of a dark color, and will always contain a small portion of protoxide and a small per cent. of soda, because the lixiviation cannot be continued for a long period, and the lies still contain small quantities of carbonic the water or lye the agitating or stirring up 7 peated strong glowing or heatin g, the quantity.

of oxide of iron must be increased in proportion.

caustic alkalies but little-loss of alkali eantake place, as the small quantity of sodafire maining with the oxide of iron after lixiviation willcomeinto use while re-employingithe latter; but a loss of, say, four to-six pericentz. mayultimately arise. A r

of August, 1882 It is obvious that in thepr'oductionof I anraware that causticsQda has been manu- 2 0 factured from sulphuretofsodium by mixture with metallic oxide, furnacing, and subsequent lixivation. I therefore do not claim the same.

I claim- The method of manufacturing caustic soda 2 5 and-caustic-potash by-heating or furnacing a mixture of carbonate of soda or carbonate of potash andoxide of ironand subsequent lixiviation, substantially as described;

This specification signed-byme this 12th day 0 r CARL LOW 1G,;

Witnesses! WILHELM WIESENHI'L'ITTER, MARTINr-KGRNER-U 

